The overall goal of the HMS LINCS Center is to delineate the fundamental principles of cellular response to perturbagens at the level of single-cells and cell populations and to make response data routinely available via web-based browse, query and programmatic interfaces. This will involve the development and testing of new measurement methods, computational algorithms, and response signatures for diverse human cell types exposed to perturbations individually and in combination. We will emphasize the systematic collection of data not currently available in existing public databases including live and fixed-cell imaging, biochemical data on signaling proteins and multi-factorial drug-response phenotypes. A focus on diverse transformed and primary cells, including those derived from healthy and diseased donors, and on clinical grade small molecules (kinase inhibitors and epigenome drugs) will increase the translational impact of our work. The proposed LINCS Center represents a continuation of a program in operation for ~3.5 years under a LINCS pilot phase U54 award. We will expand the scope and sophistication of our Center, devoting significant effort to (i) improving the quality of data analysis and visualization, particularly wih respect to the complexities of perturbagen polypharmacy (ii) accelerating the release of perturbagen-response signatures using methods that have been demonstrated to yield reliable and informative data, with a particular emphasis on primary and non-transformed cells (iii) developing and applying new measurement methods, particularly mass spectrometry for analysis of cell populations and live-cell imaging for analysis of single cells. The work will involve nine complementary but independent aims. In Data Generation, Aim 1 will perform systematic analysis of perturbagen responses at a single-cell level. Aim 2 will collect multiplex protein and mRNA data on perturbagen response using a set of complementary imaging, mass spectrometry and bead-based assays. Aim 3 will apply LINCS methods to non-transformed immune cells and induced pluripotent stem cells, and explore if signatures can guide a detailed medicinal chemistry campaign. In Data Analysis, Aim 4 will construct perturbagen-response signatures using statistical modeling, network inference and machine learning methods. Aim 5 will develop new approaches to understanding and analyzing drug interactions on multiple phenotypes in single cells. Aim 6 will develop a novel compressed sensing framework for analyzing the poly-pharmacology of kinase inhibitors. Aim 7 will enhance the query, browse and explore functions of the HMS LINCS website and database and its integration with the UCSC Genome Browser. In Community Interaction and Outreach, Aim 8 will implement diverse training and outreach activities, including collaboration with LINCS and non-LINCS research groups. In Administration, Aim 9 will ensure effective management of the Center, sustained access to tools and data produced within the LINCS Project, and compliance with program goals.